LETTER - DIFFERENTIATION OF ISOMERIC MERCAPTURIC ACID PATHWAY METABOLITES OF BENZO[A]PYRENE

Isomeric forms of the mercapturic acid pathway metabolites of benzo[a] pyrene (EP) tan be differentiated by positive-ion electrospray collisi on-induced dissociation (CID) mass spectrometry at the nanogram level, The metabolite oxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BP DE), conjugated at position 10 (bay region) with cysteine, fragments t o give characteristic ions at m/z 303 corresponding to a BP-triol cati on, these ions are not observed in the CID spectra of BPDEs conjugated at position 7 (non-bay region).